At the summit in Cannes, the billionaire prime minister played down the gravity of the economic crisis with a trademark quip, claiming that "restaurants are full and the planes fully booked."

"I go to restaurants... to do the washing up," read one banner at Saturday's mass demonstration.

Berlusconi's popularity ratings have hit a record low of 22 percent, according to the latest poll released on Wednesday.

Energised by the large turnout, Democratic Paryt boss Pier Luigi Bersani reiterated his calls for Berlusconi to step aside, accusing him of being responsible for Italy's economic woes.

"Italy is on the most exposed side of the crisis because of an incompetent and discredited government," he said after singing the Italian anthem with the crowd.

"For the country's reconstruction, we urge Italians to put us to the test government and we will show them that we can be a reform party," he said.

"The sooner we send them to the junkyard the better," read one large placard at the rally, plastered with the pictures of Berlusconi's ministers, as pressure mounted on the 75-year-old leader's government.

The placard also included pictures of his lawyer Niccolo Ghedini and Nicole Minetti, the curvaceous former showgirl who was promoted as regional councillor in Milan after serving as Berlusconi's dental hygienist.

Both are symbols of what the opposition sees as a corrupt administration.

There have been growing calls from the opposition for a national unity government to pass unpopular reforms but Berlusconi's key ally, the Northern League party, has said it would prefer early elections.

Berlusconi was quick to dismiss any suggestion that he might relinquish his job however.

"I am sorry to disappoint those who are nostalgic of the First republic when governments lasted an average of 11 months," he said in a statement.

My sense of "responsibility vis-a-vis the voters and the country... compels me and the government to continue our struggle for civilisation at a difficult time of crisis."